Wow that sounds very easy to do, thank you chaps very helpful. Mine will be bare by the weekend.
I will try a different scope but there is a deffinate pattern to the poi shift. If I only charge to 160 bar then very little poi shift or none at all. fill it up and it shoots a little high and a lot left, at about two thirds of the course it settles down and by the last six or seven targets it is back on the poa.